dave's cd player (dcd) is a simple command-line CD player. It plays CDs, loops (sequences of) tracks, plays tracks at random, and so on. Its a full featured, but simple-to-use CD player. It supports libmusicbrainz (musicbrainz.org) for CD information if desired, yet remains one of the leanest CD players out there.
DeuTex is a wad composer for Doom, Heretic, Hexen and Strife. It can be used to extract the lumps of a wad and save them as individual files. Conversely, it can also build a wad from separate files. When extracting a lump to a file, it does not just copy the raw data, it converts it to an appropriate format (such as PPM for graphics, .au for samples, etc.). When it reads files for inclusion in pwads, it does the necessary reciprocal conversions. In addition, DeuTex has functions such as merging wads, etc.
Dia is a program for creating diagrams of all kinds. The current version can do UML class diagrams, Entity-Relationship modeling, network diagrams, and much more. The engine is very flexible and dynamically loads diagram-types from disk. It stores diagrams in an XML format, but can read and write a number of different formats.
DiaCanvas is a generalized version of the drawing canvas used by DIA. It extends some features used by DIA and adds new ones, while preserving as many of the original features as possible. This project is no longer actively maintained. It is suggested that you try DiaCanvas2 instead.
DigitalDJ is an SQL-based MP3-player frontend designed for people who want to create an MP3 version of their CD collection. It is designed to work with the Grip ripping/encoding application (but can be used separately). When Grip encodes MP3 files, it will place all of the song information into an SQL database. DigitalDJ can then use this information to create playlists based on a number of criteria.
DinX (DinX is not X) is an experimental windowing system that performs clipping and drawing inside Linux kernel modules. This eliminates much context-switching between clients and the server, and makes the code small, simple and fast. It is aimed at small systems like Linux handhelds.
Disc-cover provides an easy way to produce covers for audio CDs. It scans audio CDs and uses information from the CDDB or CDINDEX database to build a back and front cover for the CD. Output is in Latex, Dvi, PDF, Postscript, HTML, plain ASCII, or any other format suited for cdlabelgen.